1. Field
One embodiment of the invention relates to an electronic apparatus having an acceleration sensor and a method of correcting an offset value of the acceleration sensor.
2. Description of the Related Art
Currently, micro electro mechanical system (MEMS) technology has been developed and a semiconductor acceleration sensor has been widely used.
For example, a notebook personal computer equipped with the acceleration sensor has been shipped. If an abnormal motion is detected by the acceleration sensor, the magnetic head of a hard disk drive is retreated so as to reduce a danger of hard disk drive crush.
Further, in some computers, the acceleration sensor is mounted on its rotatable display. By detecting the direction of the display with the acceleration sensor and automatically outputting a video signal of a resolution corresponding to a detection signal to the display, labor for user's changing the resolution is eliminated.
By the way, the output value of the acceleration sensor is strongly affected by temperatures. Thus, if the temperature changes largely, it needs to be temperature-compensated. Jpn. Pat. Appln. KOKAI Publication No. 2004-294110 has disclosed a technology for memorizing the correction amount of an offset value corresponding to each correction object temperature defined by dividing a predetermined temperature range at a predetermined interval as temperature correction data.
The acceleration sensor varies in its characteristic between one and another and sometimes the temperature characteristic of its output value indicates a completely different behavior depending on a product. However, the above-mentioned document has such a problem that it cannot absorb a difference in characteristic depending on products because the correction amount of an offset value corresponding to each correction object temperature defined by preliminary division is memorized, so that the offset value cannot be corrected accurately.